In welding this structure, the heat is equally diffused all through the mass; and thus the great evil of unequal expansion and contraction is avoided. When the steam hammer is brought into play, its face is a “swage” of circular form, calculated to clasp a large portion of the upper part, whilst a corresponding space is formed in the anvil; and by gradually turning the shaft, the whole is forged into a perfect round. The peculiar advantage gained by this mode of proceeding, is not only the facility with which heat is diffused through the mass, but that each segment is made to act like a wedge on its neighbour; thus producing the most solid forging that has yet been attained. This is rendered still more perfect, both as regards strength and durability, from the fact that a hollow axle has been produced; the great advantages of which it would be out of place to dilate upon in this work.

We trust that these anticipated misfortunes may be avoided by the construction of a more perfect shaft; and that, not only for the sake of the shareholders, but for the credit of the engineer who devised this great vessel—deservedly one of the wonders of the world. A spare shaft would be profitable ballast, if of no more value to the Leviathan.

Rolled railway-carriage axles were constructed for me with perfect success on this principle nearly twenty years ago, at the Walker Iron Works, near Newcastle-on-Tyne. The idea has, however, been in a measure “shelved;” but necessity will bring it into use again.

The only engineer who has, by practical experience, satisfied himself that large masses of wrought iron are totally useless for making heavy ordnance is Mr. Nasmyth; whose monster cannon, which was to astonish the whole world, proved, when heated, to have so little cohesion that it would scarcely hold together whilst being lifted from the furnace to the anvil. And, to his credit be it said, Mr. Nasmyth, seeing that wrought iron would not answer the purpose, manfully gave up his hopeless task. Similar experience would probably make some of our present engineers wiser men.

My experience in manufacturing the largest wrought iron guns which it is prudent to construct, sufficiently proves the truth of these assertions.

Harpoon gun-barrels, one inch and a half in the bore, having the metal at the breech end an inch and a quarter thick, will stand a proof which invariably bursts a thicker barrel; in fact, all experience tends to show that light wrought iron or steel barrels are stronger than unusually heavy ones. As all depends on the principle of condensing the fibres of the iron, ceteris paribus, the greater the condensation the greater the strength, and the less the condensation the greater the weakness.

That this argument applies principally to solid forged guns I am ready to admit; and that guns forged of hoops, rings, and bars, in smaller sections, are free from this objection, I am also ready to admit. These guns are, however, liable to objections equally fatal, both as regards their enduring and projective powers, as I shall presently show. Experience proves that brass guns are inferior, both in sharpness of shooting and in range, to cast-iron guns: this is undoubtedly attributable to the greater softness of brass than of cast iron; and for the same reason a wrought-iron gun, though made as sound as one of cast iron, would be inferior in these two important points. But when a wrought-iron gun is composed of many particles imperfectly secured (and no mechanical force is sufficient to secure perfect cohesion in large masses), the wrought becomes doubly inferior to the cast gun: a shot projected from such a gun starts from an unsound base; a large portion of the explosive force is absorbed by the variety of sections composing the gun, to the injury both of the accuracy and length of range of the projectile. The softer metals cannot be beneficially used in the construction of large guns, because they destroy the force of the expellant without making any equivalent return; and the softer the metal and the greater its substance, the more clearly is this important fact demonstrated. Thus, in experiments made with large cannon for increasing the weight of the gun beyond a certain proportion to that of the projectile, a gun of ten tons weight and ten inch bore would not exceed in range a gun of five tons, if the charge of powder were the same; on account of the indisputable fact that much more force of the expellant is destroyed, whilst more than double the force is absorbed for the recoil of the ten ton than of the five ton gun; and the loss from these two causes must materially affect the flight of the projectile, though fired at exactly the same elevation.

The great defect which experiment shows to exist in the hoop-and-stave wrought iron gun, and which renders the gun self-destroying, is separation at points between the trunnions and cascable of the gun. The force acting first upon the breech, it yields, and the force is then brought to bear upon the longitudinal portion of the gun behind the trunnions; the staves have thus to bear the first strain, and, after a few shots, become elongated. An opening of the hoops at their junction with each other (most frequently between the breech and trunnions) begins, after a very few shots, to be distinctly visible, and increases at every discharge, until further proceeding amounts to madness, or recklessness of human life.

That enormous engine, Mallet’s monster mortar, of which I give an engraving on page 100, clearly proves this to be the case. It will be observed to be constructed with a solid cast iron breech end, the dimensions of which will be seen by referring to the engraving. Abutting upon this are a succession of wrought iron hoops, ingeniously inserted into each other, and more firmly secured by six outside staves of great dimensions, which, at the muzzle ring, pass through openings in the muzzle ring, with heads like enormous rivets. The binding power is given by “quoin-like” wedges, driven through the opposite end of the stave, beneath the projection of the cast breech, giving power to tighten the longitudinal binders by a blow when required.

Dimensions.

This is notorious as a monster failure, even with a charge of powder amounting to only one half what the projector fondly hoped would be perfectly harmless in its effects. This Brobdignagian toy has proved to be fearfully expensive, the cost having been estimated at eight thousand pounds. It has, I believe, been the largest and most expensive experiment indulged in by the noble “projector,”[6] and I sincerely hope it will be the last.

The preceding pages will have done much to remove from an unbiassed mind any favourable impression of the advantages expected to result from the use of wrought-iron cannon. The knowledge of this subject, even among talented and scientific men, appears to be at a very low ebb, as is evinced by the multitude of failures that have taken place; not one success of any moment has as yet been attained, and not a discovery has been made worthy of being chronicled.

Having enlarged thus much on the qualities of a metal which it is certain can never supersede the use of cast-iron, even though it be freed from the defects found practically to exist in our present constructed iron artillery; and having also alluded to the fact that the form has much influence on the durability of cast-iron guns, I now proceed to the more important point of the qualities of cast-iron itself.

Little doubt exists that guns cast a hundred years ago were more durable than those of more recent formation; it is evident, therefore, that apart from mere form, some material depreciation must have taken place in the quality of the metal. The use of hot blast-furnaces, better fluxes, and improved chemical knowledge in the reduction of metallic ores, though highly profitable in a commercial point of view, doubling the products of our mines, and enriching their proprietors, has, unfortunately rendered English cast-iron perfectly unfit for the formation of cannon, if increased range and greater strain by high elevation are to be the order of the day.

The durability of Russian cast-iron is unquestionably greater than that manufactured in England. Some cause must exist for this; and the question arises, is the ore superior to ours, or does the superiority of Russian iron depend on their method of smelting? The latter is, we believe, the cause of the superiority of Russian iron; for experiments show that Russian ore, smelted in an English furnace, yields the same kind of cast-iron as is produced from the ore found in England. The inference, therefore, is plain, that the difference in the process of smelting makes all the difference in the quality of the iron.

Two thousand years ago the Romans, or their dependents, smelted iron in the county of Durham: vast accumulations of slag exist there at the present time; and thousands of tons have been beneficially re-smelted by two adjoining iron-works, and a percentage of iron obtained sufficient to prove that the Romans were little indebted to fluxes or hot blasts for the quality of iron they obtained. The Russians cannot boast of these adjuncts any more than the Romans: the old agents, wood and energy, are alone employed in the smelting of their ores; and in the absence of scientific aids, though they obtain a much smaller aggregate quantity of metal, yet it is undoubtedly of a much superior quality. With the Romans, also, the yield was meagre, but the quality was good; now, however, circumstances are reversed, quantity, not quality, being the order of the day.

The use of coals instead of wood in the process of smelting has introduced a mixture which is very prejudicial. Most of the coal, even from our very best mines, contains a large quantity of pyrites, or bisulphuret of iron, which, combining with the cast-iron, injures it to an incalculable extent.

These facts fully explain why our cast-iron guns are not so good now as formerly. Select the most suitable mine in the kingdom, erect a furnace on the most improved principles, employ wood fuel only, avoid fluxes and hot and cold blasts, and be content with the small amount of metal produced, and beyond all doubt the quality will be all that the most sanguine founder or artillerist could wish.

Thus the inferiority of our cast-iron guns has been accounted for, and a method suggested, which, if efficiently carried out, would effect the desired improvement.

We are indebted to Krupp for the first suggestion of, as well as the first attempt to introduce, a cast steel gun of greater durability and power than the best cast-iron gun which has yet been manufactured. Steel, possessing, as it does, hardness to any desired extent, ductility in an equal degree, tenacity unrivalled, and all the other requisites, is destined to take the place of all other metals in the construction of artillery. This metal waits only to be tested; and the greater the extent to which the trial is carried, the more confident we are that it will answer every purpose.

Krupp, like many other men with valuable ideas, has been peculiarly unfortunate in his attempts to carry them out. With a vast amount of knowledge of the science of metallurgy, he wants more knowledge in the not inferior science of projectiles; the most important point being to ascertain the form of gun calculated to be suitable for new metal, of the use of which, for cannon, the world possesses no antecedent knowledge.

The only failures Mr. Krupp has made (if they can, strictly speaking, be so called), have arisen from mal-construction, imperfect form, and unscientific combinations; defects which might be expected from a mere novice, though not from experienced artillerists or founders of artillery. The trial of the only steel gun sent by Mr. Krupp to this country, was conducted in the most absurd manner, and on wholly unscientific principles. I will endeavour to convey some idea of this most extraordinary of experiments. Whether Mr. Krupp was unacquainted with the durability of his metal, or was persuaded, against his will, to conduct the experiment as he did, I know not, but the following is what took place:—

In 1851 Mr. Krupp brought to Woolwich a specimen steel gun of ten-inch bore, weighing about four tons. He was induced (but why, I am at a loss to conceive,) to construct a cast-iron jacket, or outer gun, into which his steel gun was inserted up to the trunnions. The steel gun was separated from its cast-iron jacket by a space of half an inch in its whole length, except at each end, where the jacket was fitted to the gun with a moderate degree of tightness; thus the gun and jacket consisted of two tubes, one within the other, fastened only at their extremities, and that by a very slight force. The result, as might have been expected, was the bursting both of the gun and its case; but that the steel gun or its jacket would have stood the test, if subjected to it singly, cannot be doubted. The difference of expansion between the steel gun and its jacket would be quite enough to account for its bursting. Had the contact of the two been perfect throughout the whole length, but allowing half an inch all around for the expansion of the steel gun in that part which was subjected to the greatest pressure, the very act of restraining it in other parts so as to prevent equal expansion, would be perfectly certain to produce a fracture. Mr. Krupp’s friends have complained loudly of unfair treatment, whether justly or not, no opinion need now be given; but it is much to be regretted that his experiment was not carried out on scientific principles. The introduction of cast steel guns will be the most essential improvement in artillery: and an extensive series of experiments, extending over many years, during which time I have manufactured gun-barrels of steel alone, ought to give my opinion some weight on this subject.

Laminated steel gun-barrels were well known in 1851; but the English bugbear, prejudice, raised a clamour against them, which was echoed by interest and ignorance, and thus their general adoption was for a long time prevented. However, in the short space of seven years, they have become universally adopted, with the most beneficial results; better shooting, less annoyance from recoil, less weight to carry, and greater safety to the sportsman, being the principal. And so it will be with steel cannon; as a short time will suffice to enable scientific investigation to remove all prejudices against them.

The external form of cannon is a question of vital importance, but one which is little understood by artillerists of the present day. Whilst it is a demonstrable fact that all excessive bulk of cast-iron causes weakness in proportion to the excess, no effectual steps have as yet been taken by the Government to ascertain what is the due proportion of metal which ought to exist in different parts of the gun. The American authority on naval gunnery, Captain Dhalgren, has paid considerable attention to this subject; and if the reports on the durability of American heavy ordnance can be relied on (and there is no reason why they should not) his investigations have been attended with much success.

Captain Dhalgren has extended the principle acted upon many years ago by Mr. Monck; his great improvement consisting in lessening the weight of iron in front of the trunnions, and adding to that of the breech. In cannon, as in fowling-pieces, weight in the fore part is useless; conducing neither to the safety of the gun, nor to the smartness of its shooting. For endurance, it is necessary that the expansion should be equal in every part of the gun; rigidity in one part increasing the strain on the immediately adjacent parts, which, if much reduced, are thus rendered liable to fracture. The breech has to endure the lengthened explosion produced by the burning of the gunpowder; and, as this continues until it has overcome the inertia of the projectile, it is necessary in all cases that the maximum of strength should be in the breech of the gun. When the projectile is once in motion the strength of the tube may be rapidly decreased; the only strain it has to bear is exerted whilst the projectile is passing over it; and this strain, in properly constructed guns, becomes of shorter and shorter duration as the projectile attains its highest velocity at the muzzle of the gun. The greatest strain a gun has to bear near the muzzle is that produced by the condensation of the column of air in front of the charge; and in almost every form of English ordnance the weight of metal here is greater than is necessary.

The Russian guns which have been brought to this country present the same superabundance of metal at the muzzle, whilst at the breech there appears to be a deficiency; and when we take into consideration the extraordinary reports of their endurance, we must ascribe it to some other cause than the proper distribution of metal. Their endurance is no doubt owing in part to the goodness of the metal, in part also to the form of the breech, to the uniformity of thickness in the sides of the arch, and, lastly, to the absence of those protuberances called “reinforce rings.” These rings might with propriety be termed “rings of destruction;” for wherever irregularities exist in the substance of the metal, there the waves of vibration are interrupted, and the weak point then becomes fractured. The science of spring-making in all its varieties demonstrates the truth of this statement. Leave on a coach-spring an abutment of metal like a “reinforce ring,” and a few motions will be sufficient to break it, however well the spring may be constructed in every other part. The rigidity of this protuberance, by interrupting the waves of vibration, causes additional vibration in the adjacent and more yielding part, and thus produces fracture. The same thing occurs in all ill-constructed artillery: where the vibrations are checked, there is always a danger of some weaker part giving way. But the laws which regulate the distribution of vibrations in metal substances are not yet understood by artillerists, or cannon would be differently constructed. Those unscientific protuberances called “trunnions,” which are to be seen in almost every description of gun, prove the accuracy of my assertions. These protuberances, if scientifically considered, would soon be discarded, since they tend not only to the rapid destruction of the cannon, but also exert a most injurious influence on the direction of the projectile. The most wonderful shooting ever heard of (and which has been before alluded to) is partly to be attributed to the absence of trunnions. Trunnions act as the fulcrum of a scale-beam; they allow the breech and muzzle of the gun to oscillate, but in an opposite direction to a scale beam. Rifled cannon can never be correctly constructed whilst any weight impinges on the gun in front of the first starting point of the projectile; they must have the fulcrum behind the point of discharge, and the more nearly in a direct line the better.

Rifled cannon will in some few years be perfectly constructed of cast steel; the projectile being made of gun metal, i. e., ninety-five parts of copper to five parts of tin, or of lead and its alloys, and at a probable cost of ten times that of a cast-iron projectile of equal weight.

Rifled cannon must be elevated by raising the muzzle; no depression of the breech must occur as by the usual elevating screw; and the recoil must be received and borne by fastenings and axle in rear of the breech only. Trunnions and all impinging influences are incompatible with correctness of fire. The muzzle must be raised in a similar manner to the raising of a hand rifle, the recoil being thrown backwards, in as direct a line as possible with that of the shot.

It is only on account of the difficulty of experimenting with rifled cannon that they are at all behind rifled muskets in point of perfection. The ardent lover of science is appalled when an experiment costs hundreds of pounds. We have not a General Jacob everywhere who can afford to spend a thousand or two in experiments; but, nevertheless, the lover of science, could he experiment, might attain such extraordinary accuracy of range, as to blow up a smaller magazine than that of Kurrachee at four times the distance; and that, too, with a more certain effect, though with a projectile heavier than several of Jacob’s rifles tied together. Correct direction is certain in proportion to the increase of weight; deflection being in the minimum with the heavier weight, from the well known law of momentum. That astute and energetic sovereign, the Emperor Napoleon, is pursuing experiments with rifled cannon; with what result there can be little doubt.

It must be by the use of rifled cannon that our artillery will regain the place it has lost. A short time will suffice to make the disparity between our artillery and small arms as great as when we were content with the six-pounder field gun and old “Brown Bess.” Ranges will only be ruled by sight, and objects will be hit eventually with as much ease at 5,000 yards as they now are at 1,000. Steel, rifled cannon, and projectiles of gun-metal will assuredly bring about as complete a revolution in artillery as the Greenerian rifle and bullet have effected in small arms.

The form of gun best suited for all purposes has yet to be determined; and we have pointed out these defects in our artillery with the hope that some of the great practical philosophers of the present age may devote themselves to the study of this question. It is nearly allied to the science of bell-making, and a few more fractures of Big Ben will extend our knowledge of the subject, and produce a remedy which lies not very deep below the surface. The laws which should guide us in the construction of cast steel guns, so as to insure their durability, are very analogous to those which determine the durability of bells; for the laws which regulate disintegration of crystalline structures are very similar. Hitherto the rule of thumb has, unfortunately, been the only rule observed in measuring out the quantity of metal which shall surround that portion of a cannon which has to sustain the most violent concussion.

Professor Barlow many years ago proved, to the satisfaction of the Institution of Civil Engineers, that the metal in any cylinder decreases in utility in proportion to the square of its distance from the centre: that the outside of a gun of the form now used, in fact, is only one-ninth as useful as the inside; being three times as far from the centre. If we double the thickness, the outside, being five times as far from the centre as the inside, will be but one-twenty-fifth as useful; or in plain English, nearly useless. The reason of this is simple, and I will endeavour to explain it.

“A bar of cast iron one inch thick each way and 40 inches long will stretch about one-twentieth of an inch, if a weight of about four tons be suspended by it. When the weight is removed, the cast iron nearly recovers its previous form, and is uninjured; but if it be stretched more, by a greater weight, it is permanently injured.

“A bar of the same thickness, but three times as long—120 inches—will stretch three times as much, or three-twentieths of an inch, with the same weight; or if only one-third the weight—one ton and a third—be suspended, it will stretch one-twentieth of an inch, the same as the shorter bar.

“If we suspend 16 tons by four bars, one inch thick and 40 inches long, they will each stretch one-twentieth of an inch only, and remain uninjured; but if we attempt to do so with two bars 40 inches long and two 120 inches long, then, when the whole have lengthened one-twentieth of an inch, the short ones are exerting a force of eight tons, but the long ones that of only two and two-thirds tons. The weight, therefore, will still further lengthen the bars, and permanently injure the short ones; perhaps break them first, and then the long ones.

“This is the way a gun is burst. The inside is a series of bars of iron, say 40 inches long, in the form of a ring; the outside a series of rings, representing the bars three times as long.”

Warfare, since the first introduction of gunnery into Europe, has been like one continued series of experiments for testing the efficacy of our guns. No description of gun we now possess can lay any claim to existence fifty years ago: the great majority of our guns now in use are of a much more recent date.

With one or two exceptions, no artillery has been constructed on any scientific theory; some alteration has been made, and if a gun of a certain form and dimensions gave a certain result, then an extension or emulation of that gun was tried; and if it succeeded a loud cry of exultation was raised, and the discovery was announced to the world as a great improvement.

Colonel Prejudice has invented a vastly improved description of gun; another guess is made, and so different forms of guns are multiplied. Can there be a more striking illustration of this than the one which took place during the late Crimean war? It was boasted that the whole human race might be exterminated by the new invention; but the “Lancaster gun” turned out to be most unscientific in its construction, and most eccentric in its action. Had such a thing as scientific knowledge in gunnery existed among the artillerists of the day, such a monstrosity would have been buried soon after its birth; instead of being allowed to squander large sums of money at every discharge, and then at last to become a “Whistling Jemmy” for our bluejackets to laugh at.

The form of cannon no doubt exercises a vital influence over their durability; bad form and imperfection of material combined, tended to produce the rapid destruction of our guns during the late important struggle.

The gun which has been experimented with to the greatest extent, and which has withstood all trials successfully, is a Russian fifty-six-pounder; taken, I believe, at Bomarsund. In this gun there are two great peculiarities; the shape, as will be seen in the diagram, differs from all our own guns: it is a “chambered gun,” and the metal is taken away from the outside precisely as the contraction increases on the inside thus giving an equal thickness of metal in every part, of the arc (see page 114).

In contrast with this, we give a cut of our 8-inch gun, which most nearly resembles it as a chambered gun (see page 114).

The reader’s attention is especially directed to the dissimilarity in the distribution of the metal in the two guns. The want of uniform thickness of metal in our 8-inch gun must be sufficient to convince any one that, if the Russian gun be properly constructed, the principle of ours must be radically wrong. That such is the case, indeed, I cannot doubt, the Russian gun having undergone such a test as would have destroyed six of ours. The gun has since been made two inches larger in the bore, and even oval-bored, for firing shells, which should alone be enough to destroy it; and yet with all this the gun remains perfect.

The gun which most nearly resembles this is our English carronade; and that these guns have some important principle in their shape is proved by their great durability under all trials; and I believe that the tests to which the carronade has been subjected have been more severe than that of any other piece in the British service.

There have been many shrewd conjectures as to the cause of this durability; one of these was very pungent, viz., “the invention was not by one of the cloth.” An examination of the drawing of the 68-pounder carronade will enable the reader to perceive the great similarity between this and the Russian gun before spoken of (see page 114).

There is too much reason to doubt the proficiency of military men in the science of metallurgy; and the British system of depending solely on their knowledge for the last half century, has no doubt proved an obstacle to advancement in the science of gunnery.

The gun which ranks next is Monck’s 56-pounder. Although not a chambered gun, it will be seen, from the diagram (see p. 117), to be an attempt (if not a perfectly successful one) to obtain uniformity of thickness in every part of the arc. The durability of these guns ranks as we have placed them.

The next in rotation is the 8-inch or 68-pounder (see p. 114); which, although not the original sized gun that was rifled for the Lancaster shell, yet it was the one eventually used for that projectile up to the end of its very brief career.

The 10-inch gun of 95 cwt., delineated at page 117, will be seen to be defective in its outlines when tested by the principles before laid down, and the fact of more 10-inch guns bursting at Sebastopol than any others (mortars only excepted), may be taken as exclusive evidence of its imperfection.

The bursting of mortars is quite notorious, especially the 13-inch mortars used for sea-service in the attack on Sweaborg. A slight examination of the engraving of one will be sufficient to convince any person that, if what has already been advanced on the form of guns can lay claim to being scientific, then this is of all guns the most unscientific that was ever manufactured. Its durability, too, like its shape, is of a very low order.

The 13-inch land mortar depicted below is a much more serviceable production, because it contains much less metal.

The late Joseph Manton has the merit of being the first modern inventor of rifled cannon. His idea was, that if a motion on an axis parallel to the horizon could be given to cannon balls, they would range farther and with greater accuracy. As there exists great difficulty in causing the rifling in a gun to act upon an iron ball, he constructed a cup of wood, into which the ball was fitted, projections being made upon the wood to fit into the groves of the rifle; the spinning motion thus being communicated to the ball by its wooden adjunct. The result was twofold; for the expansions of the wood during the explosion, filled the tube of the gun tight, and effectually destroyed the windage. The government of the day did offer him a premium of one farthing each; but “Joe” over-reached himself, asking the sum of £30,000 down; this was refused, and the patent was allowed to expire without the Government taking any advantage of it, and experiments ceased to be made in this direction.

Rifled cannon have now, however, become a certainty. Mechanically speaking, they are as easily to be produced as hand rifles. The general application has, however, vast difficulties, which must be overcome before their use can become general. Small arm projectiles suitable for rifles must of necessity be made of ductile metal, and all the attempts previously made, whether with brass or iron guns, are alike useless. The mass in motion, even when of equal hardness with the gun (as in the case of cast iron guns and cast iron shot), invariably destroys that in a comparative state of rest; and the rifling is obliterated after a very few discharges. In a brass gun the destruction is certainly not so rapid, on account of the different nature of the metal; yet the destruction of the gun for all useful purposes is equally effectual. It is evident, then, that success cannot be obtained by using the present materials in rifled cannon; and the question inevitably arises, what better material can we use? Wrought iron shells have already been thoroughly tried in the Lancaster oval gun, with a well-known result.

Great hopes were at one time entertained, that something suitable would result from Mr. Bessemer’s discovery of the combustion of carbon, and that an iron of sufficient ductility, yet without the usual hardness, would be produced; but this, it appears, is still a myth.

Extent of range and accuracy of fire in gunnery will in future be of so much importance in war, that it is not extravagant to assert, that in contests between well-matched belligerents, the precious metals (if they gave any advantage to the user) would be unhesitatingly used in projectiles. But on the score of economy, science need not be impeded. Gun-metal projectiles and cast steel cannon would work as effectually together as lead and iron in small arms.

Some other mixtures less expensive might be produced (lead and copper in certain proportions are very ductile), and at the same time sufficiently strong to resist all tendency to squash; as the softer metals would inevitably do. The more ductile metals are limited in their utility, by the same law which limits the use of pure lead: that is, to given weight, height of column, or velocity. Great doubt exists whether a bullet made of gun metal, and of the same proportionate dimensions and form as an Enfield bullet, but fitted for a ten-inch gun, would not, if fired with the proportionate charge of powder (namely, seventeen pounds), be as completely squashed, or driven in upon itself, as the Enfield bullet if fired with the old Brown Bess charge of four drachms and a half.

Considerable time and experience will be required to ascertain the proportions of metallic mixture necessary to meet all contingencies; this, however, is a matter of detail, and must extend over so large an area, that it can be handled only by the government officials, with the necessary “sinews” of experiment. Nevertheless it must be undertaken; and the sooner it is done the better, for the prestige of that nation which would lead the van of improvement in gunnery, and increase its power of attack and defence beyond those of its rivals.

Rifled cannon is a generic term of endless application, presenting to the mind modifications of projectiles in endless variety, ranging from the “light firebrand” to the twice deadly rocket: not rockets of that eccentric and erratic character by which Congreve made an undying name; but real bonâ fide rifle rockets, which shall hit the dead-lights in the quarter-gallery of a frigate, carry away the halyards of your enemies’ ensign (making him drop his colours at the first shot) or dash the glass from the hand of the pilot. All such imaginary feats will yet be accomplished; though the reader may smile at the idea. My experience with rockets goes to justify me in asserting that rockets discharged from a gun, under certain circumstances, can be as effectually controlled, and kept to a direct course, as a bullet fired from a rifle. The rocket, however, may be fired a much greater distance than we have ever been able to project a bullet; because, in addition to the force which projects it from the gun, its flight is maintained by the self sustaining agency in the body of the rocket. Rockets require a much smaller charge of powder to project them than that which is used for a bullet; a rocket started by its own force, expends, in acquiring even an approximation to its highest velocity, at least one-third of the force with which it is charged; but when projected by a small charge of gunpowder this force is saved, and the flight of the rocket is afterwards sustained by the force with which it is charged.

Firing rockets from cannon can only be practised under certain circumstances. The observations already made on the granulation of gunpowder will have prepared the reader for this announcement. When fired from a cannon under the old régime, the rocket was projected at high velocity, and the case of the rocket was destroyed by the very force which set it in motion. A rocket suitable for artillery should be cast of gun metal, with a frame of considerable strength. In form it should nearly approximate to an expansive bullet; but, instead of the limited length of one and three quarters diameter; it should approach to four diameters; two of which, at least, should be appropriated to the cylinder behind the head.

The head is charged with composition more densely driven than is customary in the ordinary rocket; the tubes in the cylinder are also charged with a composition equally dense. The outer frame of the rocket is cast with suitable projections to fit the grooves of the gun: the spiral of these grooves is considerable, being one turn in every three feet, in order to impart to the rocket an effectual spinning motion when in a low state of velocity. The rocket properly constructed is then placed in the rocket-gun, and fired in the usual way; but it is essential that the gunpowder used should be of a suitable quality: its combustion must be as slow as possible, a starting velocity of from 500 to 800 feet per second being sufficient to ensure the flight of the self-sustaining projectile to the end of its range. This principle may be extended from a light firebrand, as already stated, to that of a rocket charged in the head with the most deadly and destructive fulminate.

It may appear absurd to speak of fulminates being projected; since all experiments show that fulminates, even when adulterated, will not stand the concussion of a discharge, but invariably ignite in the gun, however carefully placed or packed in the shell which contains them: for this reason fulminates have never been successfully used. But if the fulminate is placed in the head of a rocket, this objection may be obviated. The gradual manner in which velocity is given to a rocket does not subject it to violent displacement during its flight; neither need the concussion in the gun be severe, owing to the nature of the gunpowder used, which in its gradual expansion is analogous to steam: thus the field for the application of fulminates is opened to an unlimited extent.

My own experience on this subject has been limited to its application for the saving of life from shipwreck, where the application of a line to the rocket limits its range and velocity; but sufficient is left in a rocket of an inch and a half diameter effectually to carry out a line of a quarter of an inch diameter to a distance of 600 or 800 yards: that is, more than double the distance obtained by either Manby’s apparatus or the rockets now in use; which, lamentable to state, are quite inadequate to the purposes for which they are intended.

Though the improvements in rifled cannon are at present only in their infancy, they have nevertheless attained to an extraordinary degree of perfection, verifying all our predictions to the letter.

A writer in the Times makes the following statements in favour of Mr. Whitworth’s improvements:—

“While some men of really inventive talent, and a great many charlatans, have been permitted to waste the public money in trying vainly to improve our artillery, it seems passing strange that it should not long ago have been discovered how impossible it was to hope for successful results in the direction in which they were working. It was clear that while increased range and precision of firing were wanted, it was nearly as important to bring the charges of ammunition and the weight of metal in guns into more manageable proportions to each other, and to the facilities for transit on active service. No sensible man can have witnessed the frightful damage done to the efficiency of our army in the Crimea by the exigencies of the siege-train during the winter of 1854-5 without being impressed with this conviction. The principle of the rifle offered an obvious suggestion for the proper means of working out the foregoing problem; but then for artillery, rifling by grooves would not do without the use of a pliant metal in the projectile, and the cost of lead rendered its application to that purpose impracticable. It was necessary, therefore, to alter the existing mode of rifling, and to modify the bore of the cannon, so that an iron projectile could be discharged from it, rotating on its own axis in the line of flight. This result once secured, it is obvious that a field-piece or gun of position would become a rifle on a large scale, and that the same immense increase of range and of penetration which had been realised by the smaller weapon as compared with Brown Bess, would be placed at the command of the artillery service. It is consolatory, after a series of failures worthy even of Brunel in launching the Leviathan, that the country has at last the well-grounded hope of an improvement by which our ordnance may be placed on a proper footing. In pursuing those careful experiments which he undertook for the Government, principally to improve the rifle, Mr. Whitworth, the eminent machinist, adopted a polygonal spiral bore of a uniform pitch, but more rapid than could be attained by grooves. This bore has enabled him to surpass immensely the range and penetration of the Enfield rifle; but even these advantages, important as they are, scarcely surpass those which it places within the reach of our artillery service. The strain of the projectile being distributed evenly over every side of the polygon, iron can be substituted for lead in the projectile, and this simple but beautiful mechanical appliance at once becomes available for cannon.”

The powerful aid of the Times is “almost success;” though in this instance it has signally failed, the boasted accuracy there spoken of not having been yet obtained. This has no doubt arisen in part from the fact that Mr. Whitworth’s great mechanical knowledge would not suffice to make him au fait at the compound science of gunnery. His “polygonal spiral bore of uniform pitch, more rapid than could be obtained by grooves,” is after all only an experimental gun, not sufficiently developed as yet for practical utility. Still, the writer already alluded to has favoured us with the following remarks in the Times:

“Moreover, Mr. Whitworth has discovered in the course of his experiments, that according to the quickness of the turn in the polygon is the length of the projectile that may be fired; so that 24 lb. and 48 lb. shot have been sent to extraordinary ranges with half the usual charge of powder, from an ordinary 12-pounder howitzer. Here, then, is at once the solution of the whole question which has troubled the brains of so many inventors, real or pretended, for years. The artilleryman at one stride resumes the relative position to the soldier of the line which the Enfield rifle had so perilously deprived him of, and this mechanical country, after finding herself on the level of France, Russia, and other European States, is once more, as during the Peninsular campaigns, enabled to assert her natural superiority in the manufacture of cannon. We trust that no petty jealousies on the part of narrow-minded officials will be allowed to interfere with the course of Mr. Whitworth’s experiments, and that the encouragement which he is now receiving from the Minister at War and the Commander-in-Chief will enable him, at no remote date, to realise for the benefit of the army and the nation that revolution in gunnery which the results already obtained by him promise.”

Report says that 25,000l. is the amount of encouragement Mr. Whitworth has received from the Minister of War and the Commander-in-Chief; an adequate sum with which to conduct such an experiment, but not sufficient to insure success.

Of the success of Mr. Whitworth’s polygonal projectile, on a large scale, none need speculate, for the principle is self-destructive.

Lancaster’s oval shell, oscillated in its flight, took a flight so extraordinary, on account of the resistance of the atmosphere on the protuberances of the oval, that the principle may be regarded as fully established that enlarged projectiles must be smooth and free from projections that “saw the air,” otherwise range and accuracy of fire will be sacrificed. The principle of Mr. Whitworth’s polygonal bore is fully discussed in its proper place, and will here receive only a passing notice.

To Mr. W. G. Armstrong, of Newcastle-upon-Tyne, much more credit is due than can be claimed for Mr. Whitworth. Long before the paid efforts of Mr. Whitworth, Mr. Armstrong had made the subject of rifled cannon a special study, and the success of his investigations has been such as to couple his name with those of the earliest inventors of effectual rifled cannon. Mr. Armstrong may also lay claim to being an originator of wrought steel cannon; though here his name stands second as an inventor, for to Mr. Krupp is due the honour of first introducing cast steel cannon to the notice of our Government.

Mr. Armstrong tells his own tale so well in the columns of the Times that we cannot do better than quote it:—

“In the latter part of 1854, I submitted to the Duke of Newcastle, then Minister at War, a proposal for a gun which I anticipated would possess great superiority over the common forms of light artillery, and I undertook, with his Grace’s authority, to construct a field-piece in conformity with the plan I had suggested. The gun was accordingly soon afterwards made, and has since, during a period of nearly two years, been the subject of numerous experiments, partly upon the ordnance firing-ground at Shoeburyness; but principally under my own direction in this neighbourhood.

“I have hitherto avoided publicity in reference to these experiments, but, as matured results of much interest and importance have now been arrived at, and as other names are already before the public in connection with gun experiments made during the same period, I feel that I may now, without impropriety, give some information on the subject.

“With a view to strength and durability, the gun is composed internally of steel and externally of wrought iron, applied in a twisted or spiral form, as in a musket or fowling-piece. The bore is nearly two inches in diameter, and is rifled. The projectile is a pointed cylinder 6¹⁄₂ inches long, and its weight is 5 lb. It is made of cast iron, coated with lead, and is fired from the gun with a charge of 10 ounces of powder; it contains a small cavity in the centre, and may be used either as a shot or a shell. When applied as a shell, the cavity is filled with powder, and a detonating fuse is inserted in front, so as to fire the powder in the centre on striking an object. When used as a shot, the powder is omitted, and an iron point, which favours penetration, is substituted for the fuse. The gun is constructed to load at the breech, the object being not only to obviate the disadvantages of sponging and loading from the front, but also to allow the projectile to be larger in diameter than would enter at the muzzle, and thus to insure its taking the impress of the grooves and completely filling the bore. The piece weighs 5 cwt., and is mounted upon a carriage which bears a general resemblance to that of an ordinary 6-pounder field gun, but which embraces a pivot frame and recoil slide. A screw is also applied, not only for elevating and depressing the gun, but also for moving it horizontally, by which means great delicacy of aim is effected. The recoil slide has an upward inclination, which enables the gun, after running back, to recover its position by gravity; and its use is to relieve the pivot-frame and adjusting screws from injurious concussion.

“I shall now give some particulars of the experiments recently made with this gun on the coast of Northumberland, near the village of Whitley, under the official inspection of Colonel Wilmot.

“Fourteen shots were in the first instance fired from a distance of 1,500 yards at a timber butt, 5 ft. wide 7¹⁄₂ ft. high. Six of these were expended in finding the elevation proper for the distance, but after that was determined every succeeding shot hit the object without previous graze. The final elevation of the gun was 4 deg. 26 min., and the mean lateral distance of the shot-marks from a vertical line through the centre of the butt was only 11¹⁄₂ in.

“Persons who are conversant with artillery practice will be able to appreciate the accuracy of this firing; but, for the information of those who are unacquainted with the subject, I may state that the ordinary 6-pounder field-piece, which in point of weight forms the nearest approach to the present gun, is perfectly useless at a distance of 1,500 yards, and is very uncertain even at 1,000 yards. It is only, therefore, with heavy artillery that a comparison can be drawn; and it will be sufficient to state that in tabulating the practice made with such ordnance the deflections are invariably recorded in yards, whereas with this rifled gun they can only be properly given in inches.

“With respect to penetration, the following particulars will be regarded as equally remarkable, considering the small weight of the shot and the length of the range. The butt was 3 ft. thick, and was composed of six layers of rock elm bolted together, so as to form a solid block. One shot passed entirely through; another struck near the edge and glanced; and the remaining six penetrated within a few inches of the opposite side.

“Shell firing was next tried at a distance of 1,500 yards; the gun being fired at the same elevation and with the same charge as in the previous practice at the butt.

“In this case two targets were erected, one behind the other, so as to appear as one object when viewed from the gun, and a space of 30 feet was left between them. The front target was intended to exhibit the perforations of the shell before bursting, and the back one to show the effect of the fragments resulting from explosion.

“After some preliminary experiments twenty-two shells were fired at the front target, and of these only one missed the object of aim. The following are the particulars:—Seventeen hit the first target direct, and burst behind it, the fragments penetrating the second one; three grazed and burst immediately in front of the first target, and perforated both with the pieces; one hit the bottom of the first target and exploded in the ground, and the remaining one missed entirely and burst on some rocks nearly on line beyond. A strong side wind was blowing at the time, and accounted for the deviation of this single shell.

“Four shells and three shots were then fired at an elevation of 6 degrees, from a distance of 2,000, or, more accurately, 1,964 yards. All these struck within the breadth of the target; but the elevation being scarcely sufficient, they all fell a little short, except one shell, which, ranging somewhat further than the others, hit the target and burst as usual.

“The results of this shell-firing were as follows:—The front target contained 51 holes, and the back one 164, while the ground between and adjacent to the targets exhibited about 70 perforations by fragments of shells, the greater portion of which were afterwards recovered by digging.

“With respect to ranges exceeding 2,000 yards, I may state that on previous occasions the gun had been tried up to 3,000 yards—a distance which was reached with an elevation of 11 deg., and the usual charge of 10 ounces of powder, or 1-8th the weight of the projectile. By augmenting the charge the range is increased, but the accuracy is impaired; and I therefore adhere to the 10-ounce charge, which gives ample penetration, as the experiments at the butt will testify. I may also observe that the ranges obtained with this charge bear a favourable comparison with those of the heaviest round-shot guns fired with a much larger proportion of powder.

“It is a curious fact, and one which greatly increases the efficiency of the shells, that owing to the bursting charge requiring a minute space of time to mature its ignition after the firing of the fuse by impact, the shell is enabled to travel four or five feet after striking an object before disruption takes place. Hence, therefore, it acts as a shot before it bursts as a shell. When it perforates a target the explosion may be seen to take place at a few feet beyond, and when it grazes it has time to rise, and may be observed to burst after clearing the ground. If, therefore, it were fired against a ship, it would first penetrate the side in its entirety, and then, bursting, traverse the deck in fragments; or if directed against troops, it would pierce the front line as a bullet, and operate like grape-shot beyond. The shells explode with equal certainty whether the first substance struck be hard or soft; and, in fact, they even burst on the surface of water, provided the elevation of the gun be not too great. The bursting charge is very small, but it suffices to break the shell into about 30 pieces, which pursue their forward course without too much dispersion.

“It is impossible to contemplate the results obtained with this gun without being impressed with the important part it is calculated to perform in warfare. Opposed to any ordinary field-piece, it would be like the Greener rifle against the old musket; and no gun could be worked at an embrasure if a fire of shells were directed against it by one of these rifled pieces placed within the distance of a mile. In naval operations, also, guns of this description, but of larger size, might apparently be applied with great effect—more especially as a system of breech loading, combined with a self-recovering recoil action, would be peculiarly advantageous in firing from portholes. Even light 5-pounders, sending their shells from great distances through the sides of a ship and sweeping the decks with fragments of lead and iron, would produce very destructive effects; and a small swift steamer carrying a few such guns might prove a very troublesome opponent to a large ship of war. But if the dimensions of the gun were increased so as to adapt it for shells of 20 lb. or 30 lb., still more terrible injury could be inflicted at greater distances; and the ponderous artillery now used at sea would be of little service when opposed to the accurate and long-range firing of such rifled shell-guns.”

Since the publication of these remarks, rifled artillery of Mr. Armstrong’s production has, we believe, been extensively tried. The results of these trials have been most extraordinary; and the principle is, we believe, identical with the expansive principle bearing my cognomen: an extension of the principle of the Greener and Enfield rifle, hereafter to be described. I have had the honour of being consulted both by English and foreign authorities, and I have assisted in constructing rifled artillery for several years; and the experience thus obtained justifies me in making known to the world some of my observations on this subject.

Rifled cannon with elongated projectiles, similar in shape and principle to the Greenerian bullet, give, with charges inferior to those of the old régime and calibre, more than double the range, with ten times greater accuracy.

Now, either of these points, if gained, would be most important improvements, and when combined would produce the most extraordinary results. But this is not all: a great diminution in the weight of the gun might also be effected; and these advantages may be still further extended when we have had time to increase our knowledge of the valuable materials with which we are only just now becoming acquainted.

The following table will show the advantages to be gained both in length and accuracy of range.

Before reverting to the table, it may be necessary to remind the reader that the great reduction in the weight of guns arises from the adoption of the elongated projectile. For example: the diameter of the elongated projectile for an “18-pounder” is much less than the diameter of the gun for the spherical 18-pounder; thus allowing the thickness of metal to be equal in both guns. The gun for the elongated projectile may be greatly reduced in weight without at all diminishing its strength, simply on account of the great diminution in the diameter of the arc.

There is another important fact, which Mr. Whitworth, with all his boasting, has carefully concealed: viz., that a much greater pressure is exerted upon the square inch in the lesser than in the larger diameter of bore; and to conceal this fact, whilst claiming merit for a bullet of 50-gauge exceeding in range one of 25-gauge, the charge of gunpowder being alike in both cases, appears very like deception. Any engineer will tell us that the pressure in the lesser is twice as great as in the larger bore; and this explains why greater velocity is given to the projectile.

With these explanations the reader will be better prepared to weigh carefully my observations. My task would, doubtless, have been rendered more easy, if a clear elucidation of the principles of the expansive bullet could have been given thus early in the work; but it is thought better to do this in its proper place. I will only add here, that although two bullets, one elongated, the other spherical, and of equal diameter, meet with the same amount of atmospheric resistance, yet the one containing twice as much matter as the other retains its medium velocity nearly double the distance. With these explanatory remarks I give the following table:—

The reader must understand that all the guns given in this table were not rifled, and that they have not all been subjected to trial. The 6, 12, 18, 24, and 48-pounders have been tried, with the results given above; but the heavier guns have not as yet been tested: the ranges and weights given in the table have, however, been derived from the results yielded in the trial of the lesser guns, and may be safely relied on as scientific data; being, in truth, rather under than over the mark.

All experiments clearly establish one very important principle, long known to those acquainted with the science of projectiles, viz., “That the heavier the projectile, the less the deflection.” Thus it is quite possible that the longest ranges may ultimately be obtained without any perceptible deflection. And when we observe that the deflection of an ordinary 32-shot in a range of 2,000 yards, is 50 feet, and in 2,500 yards, 80 feet, whilst the elongated shot, at a much greater distance, is not deflected half as many inches, I think we may fairly say that our knowledge of gunnery is yet in its infancy. Fulminating powder may be used as an auxiliary in shells for various important purposes; such, for instance, as destroying an entire fleet; and it is clearly within the range of possibility that by its agency the largest ship may be destroyed by a single shot. The accuracy of rifled cannon renders it an easy task to strike a plank only one inch above the water line, and the penetration of an elongated gun-metal or lead-alloyed shell would enable us to reach the innermost parts of the magazine: for it is scarcely possible to produce even an iron casing which shall resist the power of such projectiles. It is possible, therefore, that we may see the noblest fleet destroyed in a few minutes by the agency of such projectiles.

I will endeavour to give an outline of the method by which this may be effected. A long rifled cannon, constructed for an elongated gun-metal shell; of from fifty-six to eighty-six pounds, and with an extreme range of from 6,000 to 7,000 yards, may be considered to be a suitable instrument. This shell should be charged in the head with a given quantity of the fulminate, such as would be most calculated to prevent the tendency to explode from the concussion produced by the discharge of the gun. It will be necessary to place the fulminate in thin layers between sheets of prepared caoutchouc, or some other preparation of India-rubber; having thus arranged the fulminate in the head of the shell and secured it there, the usual method of filling the remainder is resorted to, and the aperture is securely screwed up: fuses not being necessary in this arrangement.

The difficulty in using this shell is to prevent its explosion when the gun is discharged; and to obviate this all our engineering skill is required. Time and experience will show that, by a modification of the propelling agent, the shell may be started from a rifled cannon at a very low velocity; the velocity being increased like that of the rocket. This is to be done by modifying the arrangement of the gunpowder so as to ensure the shell acquiring its greatest velocity as it leaves the muzzle of the cannon. The result of this has been already shown. On the shell striking any object, such as the ship’s side, the metal of the shell is driven in upon itself, and an explosion of the fulminate follows as a natural consequence. Experiment has proved that shells exploding as they strike the ship’s sides, produce very little damage beyond making a hole in the ship the size of the shell. This, no doubt, arises from the short space of time occupied by the shell in passing through the side of the ship; all its force being exerted in the interior instead of on the sides of the vessel. All shells of the nature alluded to would, at certain distances, take such a line of flight as to ensure them dipping towards the centre of gravity, and thus exploding the magazines, however deep below the water-line; and when we consider the destructive effects of fulminates, we think it quite within the range of probability that they might produce all the effects we have spoken of.